Post on 24-Jan-2022
Chapter 4 Genes and Their Evolution:
Population Genetics
Demes, Reproductive Isolation, and species
What is a population?
– Fluid concept
–Groups beneath species level?
• Deme (local breeding population)
• Subspecies, (Race)
• Gene pool
Demes, Reproductive Isolation, and species
• Reproductive isolation
–Microevolution
–Macroevolution
Figure 4.3a
Microevolution
Macroevolution
Figure 4.3b
Hardy-Weinberg Law: Testing the Conditions of Genetic Equilibrium
p2 +2pq + q2= 1
p=A
q=a
Mutation: The only source of New Allelles • Point mutations • Transposable elements • Klinefelter’s syndrome • Nonsynonymous point mutation • Induced mutations • mutagens
Natural Selection: Advantageous characteristics, survival and
reproduction
• Fitness
• Directional Selection
• Stabilizing selection
• Disruptive selection
Figure 4.9
Industrial Melanism
Melanic/Nonmelanic
Natural Selection in Humans: Abnormal hemoglobins and resistance to malaria
• Positive selection
• Hemolytic anemias
• Hemoglobinopathies
• Ballanced polymorphism
• Capillaries
Genetic Drift: Genetic Change due to chance
• Founder effect and genetic bottleneck
• More important with small populations
• exogamous
Gene flow: Spread of genes across population Boundaries
• Admixture Tends to make populations genetically similar, offset problems of inbreeding